The invention relates to an electric lamp comprising
a glass lamp vessel having a pinch seal and an axis, an electric element in the lamp vessel, and current supply conductors extending from the electric element through the pinch seal to the exterior.
The pinch seal has an end face transverse to the axis of the lamp vessel, two opposite major side faces and two opposite minor side faces.
Each of the minor side faces has a groove, which extends as far as a respective major side face. The grooves have the axis of the lamp vessel as the axis of symmetry.
Such a lamp is known from DE AS 16 39 093 corresponding to Great Britain Patent 1,214,736.
The invention further relates to a holder for the lamp.
The known lamp has for its object to provide a solution for the problem that lamps whose pinch seal is provided with grooves cooperating with resilient holding members in the lamp holder can become detached from the lamp holder if they are subjected to shocks or vibrations.
In the known lamp, this problem is solved in that the grooves extend obliquely with respect to the axis of the lamp vessel in such a manner that, from the relevant ma]or side face, they approach the end face of the pinch seal more and more closely. When a lamp is arranged in a holder, the lamp must be inserted deeply and must then be rotated about its axis in order to introduce rigid holding members of the lamp holder into the grooves. The lamp is then given a final position which is located less deeply in the lamp holder than upon insertion. When the lamp is arranged in the lamp holder, the lamp therefore performs a bayonet-like movement. Elastic means of the lamp holder hold the lamp in a final position which is located less deeply in the lamp holder than the initial position of the lamp after insertion and before rotation.
The known lamp has a number of great disadvantages.
When the lamp is inserted, it must be translated and rotated. In case a luminaire must be provided with a large number of lamps, such as, for example, a matrix panel for, for example, traffic signalization, the lamp requires very complicated equipment to provide a panel with all the lamps required simultaneously in one operation.
Since when the lamp is inserted in a lamp holder, it must first be positioned so that the grooves are located beside the holding members in order that these holding members can be introduced into the grooves by rotation of the lamp, the lamp holder must be comparatively commodious and the lamp has lateral space in the lamp holder.
The depth position of the lamp in the lamp holder depends upon the effect of the elastic means of the lamp holder. Consequently, it is uncertain what depth a lamp will ultimately have in a lamp holder.